I just looked at Blackley's website. They have a couple of wheellock casting sets. Their German wheellock set, with the brass wheel cover, appears to be identical to the one sold by The Rifle Shoppe. I bought this lock from TRS a little over a year ago, assembled, for a little over $700. (I didn't think I had the experience or tools necessary to assemble a wheellock from just the parts castings.) I was very pleasantly surprised that TRS assembled and sent this lock to me in just a few weeks! I finished my wheellock rifle using this lock bit earlier this year, and posted pictures of it on this site a few months ago. Anyway, if the German type wheellock is what you're looking for, it looks like both Blackley's and TRS have the same exact parts, but TRS can assemble them for you, and if your luck is as good as mine, can send your lock in just a few weeks. I found it works best to actually call TRS by phone during working hours and talk to them in person about what they have available. I never have gotten responses from them when I sent e-mails.
Best,
Hemo